It is not possible to move the site without files transfer. First you have to change the server of the site and than transfer all files with FTP or whatever ( and databases, i guess ). Is that, what you mean?

Thanks for your respose, but I think it is possible, because of folder structure with a script. I change the server, and the Ispconfig create the domain's vhost, user, database on the other one, then move data, check it, then remove from the old server. The Ispconfig database store the domain datas like user, folder, database name and user, ftp user and of course the passwords. Everythig is a $variable...

One additional question about migration, I want to migrate only some sites to new server. Is it possible to retain their paths on new server?
- delete website site.com from server1
path was /var/www/clients/client1/web145/
- create site site.com on server2
path is now /var/www/clients/client1/web564/